


crimson light

by chosuiri



Category: Fate/Grand Order, Fate/stay night & Related Fandoms
Genre: (sighing ) i know i love pain, Angst with a Happy Ending, Hanahaki Disease, Implied Sexual Content, M/M, is merlin helpful? doubtful.
Language: English
Status: Completed
Published: 2019-04-28
Updated: 2019-04-28
Packaged: 2020-02-09 07:03:55
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,306
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18633199
Author URL: https://archiveofourown.org/users/chosuiri/pseuds/chosuiri
Summary: “Right, then that explains things. Let's put it this way… you got a funky disease here that won't be cured unless your unrequited love is fulfilled.” Merlin states with a sympathetic smile.“... then it sounds like I will die from this disease, if it's as you say.” Diarmuid mumbles quietly, grabbing one of the roses from the box and carefully stroking its petals. He plucks the petals off, one by one.Knowing the disdain fate held for him, Diarmuid doesn't anticipate this story having a happy ending.





	crimson light

**Author's Note:**

> me: diarcu hanahaki  
> nyx: do NOT
> 
> so here we are again in rarepair hell...  
> no one gives proto rights so im here to give him some rights because THAT'S my puppy baby and he always comes with diarmuid in 10 summons so im just saying... theyre boyfriends.

It started after a hunting trip with Cú Chulainn.

Diarmuid got back to his quarters that night and started to cough violently, confused when he found out that there was a rose petal in his throat. The petal was pure white, reminding him of the very same flowers he gifted his Master.

Strange.

Uncertain if he should report the abnormality immediately to his Master, he first considers that it must be some sort of misunderstanding. Maybe he accidentally ingested a rose petal… somehow. He takes a container he filled with chocolates he received from some of Chaldea's staff members from Valentine's Day last month and empties its contents atop his drawers. He places the rose petal where the chocolates once resided. He shuts the container, stowing it away in his drawer. If it becomes a problem, he would consult the doctor or Da Vinci about it.

However, now is a better time than any to eat chocolates laden with admiration.

His mind supplies that all these women gave it to them because they fell for his cursed spot.

The chocolates start to taste bitter.

* * *

His smile is bright and toothy with his canines fully visible as he waves Diarmuid next to him. He's like a breath of fresh air with his sunny deposition, and it makes Diarmuid sure that he's certainly the Child of Light.

They were summoned together, the two of them, and had been paired together as twin Lancers ever since. Cú lives up to his Hound status, hair fluffy to a fault and as fierce as his companion in his life. He's more free spirited than Diarmuid would ever allow himself, and speaks his mind without missing a beat.

Seeing him smile makes Diarmuid crack a smile back, and his heart starts to pound quickly in a fluttery tempo.

Somehow, Diarmuid feels unstoppable with him. Ireland's Child of Light, which had once seemed so far away, is smiling at him like this and saying his name.

It's strange. Diarmuid didn't plan to fall in love again. The pain from Grainne remained heavy in his heart, knowing that her love may have not been true. She still treated him kindly and warned him to the end, but her love for him was not the same as his love for her.

Knowing the disdain fate held for him, Diarmuid doesn't anticipate this story having a happy ending. His heart flutters as it sings praises of Cú Chulainn, and foolishly, it hangs onto hope.

Diarmuid's still an optimist. He won't ever know if his love will be fulfilled because he plans on keeping his love concealed.

“Diar, ya there?” Cú laughs as Diarmuid looks up with a bewildered expression. “Yer so spacy lately.”

“My apologies,” Diarmuid returns quietly, “it seems like I was distracted. I was… just thinking about some things.”

“Oooh. Mind tellin’?” Cú blinks, resting his chin on the palm of his hand as he leans in slightly. Before that, his nose crinkles as he leans in slightly closer to Diarmuid to sniff him. “Ya smell like chocolate. Ooh… lady problems?”

 _Quite the opposite_ , Diarmuid grumbles in his mind, but shakes his head. His cheeks flushed from the small act of intimacy, Diarmuid pulls back. No more than this. He clenches his fists, unwilling to be so cruel to the object of his affections… but he was too close. “No. I was just eating some of the chocolate I got from Valentine's Day… excuse me, Cú.”

He leaves the cafeteria and a bewildered Cú behind as he briskly returns to his quarters. Some other servants try to stop him out of concern, but he gracefully wards them off as he makes it his number one priority to get to his room.

He finally reaches his room, and as soon as he shuts the door, he begins to cough violently again. It's worse than the first time, his eyes widening in realization at the array of yellow rose petals falling into his palm. When did he ever ingest the namesake of one of his spears? Diarmuid reaches for the container where the first rose petal was, noticing that it somehow stayed fresh and had not yet withered. He bites his lip as he dumps the new pile of yellow rose petals inside.

* * *

“Diarmuid, are you okay?” His master asks, concern etching itself in her features as she looks upon him.

He nods mutely, trying to avert his gaze as he launches into another coughing fit.

Cú blinks, reaching a hand out to comfort him, but immediately Diarmuid slaps it away. “Diar?”

“Don't worry about me. I can still keep going.” The lancer asserts with a small reassuring smile, discreetly scattering the flower petals where neither his master or the other servants could see. He rematerializes his spears in his hands, and looks over to his Master. “I apologize for that. It seems like I choked on my own saliva…”

Cú doesn't even laugh. No one does at what would seem to be a ludicrous act, but the worry on their faces only grow stronger.

“Diarmuid. Why not stay in the back? You're not in fit condition--”

“Master, I am fine. My spears have not lost their luster. That was only a minor setback.” His voice grows raspy, even more desperate than before as he pleads to her.

“Yer feckin’ stupid.” Cú snaps, shooting a glare at him as he administers a flick to Diarmuid's nose. “Yer an important ally. My friend. No way in hell am I lettin’ ya fight when yer in bad shape.”

“Friend…” Diarmuid repeats quietly, eyes downcast, but allows the other lancer to continue.

“I'm sayin’ ya gotta take care of yerself,” Cú continues, “how ya gonna protect otherwise? And hey, aren't ya underestimating the rest of us?”

His heart throbs. Sure, the Knights of Fianna were supportive of each other and looked after each other, yet… he hasn't ever been told so bluntly that he needs to have more regard for himself.

Diarmuid rarely heeded others advice when it counted. He didn't listen to Grainne when she warned him. He hasn't changed. He twirls his spear, for his pride as a warrior is being tested.

“Thank you, Cù, but… it's really nothing. You must be underestimating _me_ if you think I can't handle a few enemies like this.” He returns, but that earns a groan and a shaking head from Cú.

“Confident, aren't ya?” He snorts with a small smile, “guess yer pretty stubborn. Don't make things tough for Master!”

“Of course not,” Diarmuid retorts with a matching smirk, “you trouble Master more than I do, you know?”

“Arse,” Cú snickers as he readies his own spear. Their Master offers them a dejected smile, but allows Diarmuid to proceed in combat.

That night, petals turned into full red blooms. It's more painful than ever, but Diarmuid quietly takes the roses and place them in the same container.

It's painful, but for some reason, Diarmuid finds it beautiful. If only he knew _why_ this was happening.

He examines the roses, gingerly touching a hand to his chest. It feels thick, as if his lungs were being constrained.

The itch in his throat causes him to cough again, and he spits out another red rose bloom.

He wonders if it was dyed red from his blood.

* * *

He decides to consult the Magus of Flowers. Hesitant to approach such an esteemed heroic spirit, he chose to first ask Artoria to help him meet with Merlin. She kindly led him to his quarters, and introduced Diarmuid to him.

But for the sake of keeping this under wraps, he requested for her to leave the room.

“She's gone for certain,” Merlin announces with a wink, “it's not very knightly to eavesdrop, after all.”

“O-Of course,” Diarmuid stutters, flustered at the thought that he _doubted_ his friend for a moment there. “Either way… thank you again for letting me talk to you, Magus of Flowers.”

“No, no, thank you. I'm honored to help out such a beautiful young warrior like you!” Merlin smiles as he playfully nudges Diarmuid with his staff. “Now, it seems like you suffer from some sort of ailment…”

Right. Clairvoyance. “Yes,” Diarmuid produces his container of roses, and opens it for Merlin to look. “It's a strange occurrence, but I've been coughing up flower petals, and yesterday they have turned into entire flowers.”

Merlin hums thoughtfully, and then pokes Diarmuid's chest, “has your chest been feeling tight?”

The lancer winces from the sudden contact, but nods slowly. “It's been feeling tighter… and a bit harder to breathe. Why?”

“You really have a tragic record with love. How strange, your love spot is sure to make any woman fall in love with you. Of course not for the right reasons, but if it's like that, there is no reason that you'd have this.”

“Why does that matter?”

Merlin laughs, “it has something to do with love, of course. May I ask who the lucky person is? Anyone's fine! Ah, but no touching Artoria! You'd have to get my approval first--”

Diarmuid's cheeks turn red as he attempts to avoid Merlin's gaze. “Not at all. It's… a man. And it's impossible for my love to ever be returned.”

“You don't know that,” Merlin supplies, but his smile faltering. “Right, then that explains things. Let's put it this way… you got a funky disease here that won't be cured unless your unrequited love is fulfilled. _Hanahaki._ ”

“... then it sounds like I will die from this disease, if it's as you say.” Diarmuid mumbles quietly, grabbing one of the roses from the box and carefully stroking its petals. He plucks the petals off, one by one.

“Well… let's also say I have my ways of curing it in a different way.” The caster explains, “if you're willing to abandon love altogether. Or I can give you amnesia, but I think the former is a more reliable choice!”

“Love has wronged me many times,” Diarmuid laughs softly, “so perhaps that would be better… without love I could become a better knight.”

“Not just romantic love. I would be taking away your capability to love anything… no friendship, no nothing. You would only be able to hate or able to be neutral.” Merlin warns, “are you certain? Also, there comes risks for me fiddling with your spirit origin so much… it might make you into someone different altogether.”

Diarmuid pauses. Someone different… no, a knight without love is no better than a weapon. What protection could he do then if he felt nothing?

The other method, Diarmuid surmises, is that Merlin takes away his love for Cú by sealing the memories they shared, and possibly his feelings for him in general.

Merlin reaches over, taking a rose for himself. “What will you do, First Spear of Fianna?”

Diarmuid shuts the box of roses. With a pained smile, he dips his head as he answers, “I want to keep my ability to love. If I die, then Master can try to summon me again… well, also, it's not like she will need me around. She has plenty of other Lancers stronger than myself.”

“A romantic, aren't you?” Merlin quips gently, and lets out a sigh. “If that is what you decided on. You may think little of yourself, but others value you greatly. Diarmuid, why don't you ever oppose fate? You've cursed it and resented it for how it miserably ended your life, but what have you done to fight it?”

Diarmuid blinks, taken aback by the caster's observations. “I have, haven't I? I made sure to make amends for my past sins, so that I--”

He's cut off by another bout of coughing, and rose petals fall and flutter toward Merlin's bedroom floor along with full rose blossoms that Diarmuid manages to catch with his hand.

“Then there's something you can do,” Merlin bends over slightly to pick up another petal from the floor. He twirls it and pinches it between his index finger and his thumb. “Make your love requited. Once you know it is, then it'll stop.”

“How?” Diarmuid for a moment thinks to help Merlin for magical assistance, but that wouldn't be right. That's no different from utilizing his love spot to his advantage. No, he wanted Cú to love him back for himself… and he has to do this in the way do Cú doesn't know about his disease.

“No… I think I figured things out. Thank you, Merlin.” Diarmuid dips his head in reverence, thinking for all his obscenities, the caster was pretty reliable. Of course, he's one who advised Artoria and made her king. Someone like a father to her.

With a hint of a smile, Diarmuid thinks back to his own foster father-- perhaps he would've said the same thing.

“Haha, I wonder what will happen?” Merlin winks, “y'know… if it doesn't work out, I'll erase your memories and you can fall in love with me.”

Diarmuid rolls his eyes. “That is obviously out of the question.”

* * *

After that fight, his Master had been keeping more tabs on him lately. And it seems like she assigned Cú to that task, making the symptoms stronger by each day as he finds something new to love about the Hound.

His heart is golden through and through, similar to Diarmuid he helps out anyone whenever he can. And despite itching to spar, Cú never offers.

Diarmuid offers himself, but Cú always wrinkles his nose and says he's not allowed to strain himself more than necessary.

He has seen Cú be angry countless times, and he barked at other servants and staff members that even talked to Diarmuid as if he was his personal guard dog.

For certain, this arrangement has not been doing Diarmuid any better. He doesn't think it'll count if he obligates Cú into loving him back because of his disease. But Cú being around him as much as possible is making is harder to hide the symptoms.

He finally asks, beginning to fear that his time is running out. “Cú, are you just doing this because Master asked you to? I hate to be wasting your time like this… as you've seen, I'm perfectly fine.”

Cú blinks, repositioning his spear so it rests easily on his shoulder. “Stupid, I'm the one who made her let me do this. I'm worried yer gonna get hurt or somethin’! It's what friends do, yeah?”

“Yeah…” Diarmuid agrees weakly, “that's right. Friendship is a beautiful thing.” He chokes out, cursing himself for being too scared to tell Cú his true feelings.

Then Cú flashes him that toothy smile again. His heart soars at the sight, and he wants nothing more than to kiss him endlessly, run his fingers through his fluffy mop of hair, and see Cú red to his ears.

Maybe if nothing else, he can sleep with him once before he dies. Diarmuid is too much of a romantic and wants to do this properly-- but maybe he can… act selfishly for once.

“Cú, do you mind closing your eyes for a moment?” His own voice sounds so foreign to him. So assertive, reminiscent of how Diarmuid feels while he's engaged in combat.

Cú looks bewildered, but nods. As soon as Cú closes his eyes, Diarmuid's breath hitches. He looks so vulnerable. It's too unfair.

He leans in closer, inhaling and drinking in Cú's scent. His eyes flit all over the kissable spots on Cú's face, and finally he settles for the very end of his lips. A strange location-- close enough to the lips, but far enough at the same time.

“Sly bastard,” Cú grabs ahold of him, resting a hand firmly on his shoulder. His fingers dig into Diarmuid's shoulder, a low rumbling in Cú's throat starts as he opens his eyes. “Ya missed.”

Diarmuid's eyes widen, surprised at how it seems that Cú returns some of the sentiments. Or maybe he's just craving intimacy that he's settling on Diarmuid to sate it. He pulls away, opening his mouth to sputter an apology, but Cú soon overtakes it by pressing his lips against his.

His kiss is hungry. Desperate as Cú is quick to add tongue. It's passionate, and way more heated than Diarmuid ever anticipated. He returns it with as much passion and vigor-- even more.

Finally, Diarmuid pulls away to catch his breath. It's not a dream, is it? No, maybe Cú is just wanting physical relations. Nothing more. Friends with benefits.

This is the closest thing he'll get to the romance he desires, so he'll go with it.

“We're not stoppin’ there.” Cú smirks.

Diarmuid's cheeks heat up, melting by the intensity of his gaze. “Let's do this elsewhere.”

* * *

Diarmuid wakes up very warm. Rising early at 6 AM as always, he somehow feels the definite lull to go back to sleep. To keep resting here as if there were no problems. To stay here with Cú and pretend that they were passionate lovers who couldn't bear to rise without the other. He turns his head slightly, looking fondly at the other lancer snoozing away quietly with his arms wrapped around Diarmuid's body. Well, it's not like he could go anywhere without waking him up.

He thinks about his duties today. To do more training and improve on more shortcomings so Master deems that he is in fine enough condition to take him out again. The other was to find a way to get Cú to love him back.

He allows himself to float back into sleep.

He doesn't realize that there is no longer a straining tightness in his chest, and has completely neglected the fact that he hadn't been coughing up flowers the whole night.

* * *

He wakes up to Cú peering at him with bright red eyes and the most gentle smile he could ever imagine. “Mornin’ sleepyhead.” Cú's blue hair splayed itself all over his chest, reminding Diarmuid that he had taken out the ponytail during last night's activities.

“Good morning, Cú,” he returns in a whisper, wanting to selfishly savor this moment as lovers and begins to stroke Cú's cheek.

The other chuckles at this, pressing a kiss on Diarmuid's hand. “Glad I could wake up like this with ya.”

“I'm quite fortunate,” Diarmuid smiles, uncertain how he should broach on how Cú defines his relationship. His actions are far too tender to be just friendship, but Diarmuid doesn't want to read into it too much.

Cú goes in for another kiss, this time it being shorter and sweeter than their first kiss. He pulls away with a dazed and goofy smile. “I'm the lucky one here. I'm dumb, so I didn't get it until ya kissed me. Well, did that cop-out kiss, anyways.”

“You… mean..?” Diarmuid starts slowly, his heart pounding quickly as he tries to not to jump to conclusions. “I love you, Cú. I've always admired you, but being able to fight along your side and being your companion has been a true honor. With spending so much time with you, I can say with full confidence that I am in love with you.”

He leaves the part out about that he knew for certain as he was coughing up flowers to prove it. That seems to be over now with him effectively challenging his fate and curing himself. He can breathe now-- so he breathes Cú in again as he waits for his response.

“I love ya too, Diar.” Cú grins, crawling on top of Diarmuid's body and then embracing him from above. “I'm not that good at words like ya, but I can show it. Ready for another round?”

Diarmuid laughs, “I suppose I have to be.” He wraps his arms around Cu, pulling him closer as he has the two of them lie there peacefully for a moment.

**Author's Note:**

> why yes the order of the color of the roses is relevant :) i decided to go with roses for their traditional association with love + diar's strong association with rose motifs... they don't make it obvious but his noble phantasms are literally called crimson rose of exorcism and yellow rose of mortality. and ofc he gives u roses on vday as a return gift so you KNOW those are his favorite flowers.
> 
> thank you so much for reading! this was my first time writing hanahaki tbh... i've always wanted to try it but never actually did it until i felt obligated to whip this out. anyways.
> 
> scream at me on twitter @shineonthesea... or i would say but twitter axed that account, but u can find me [here](https://twitter.com/firstspears) now.


End file.
